Get the program "SuperDuper". Do a search for it and it's free.
Mount the new HD in your system and the old HD in a USB enclosure.
At boot time, hold down the "option" key and select the external (original HD) to boot from.
After you boot up, run SuperDuper and copy the external HD to the new internal HD. It will create an exact replica of your original HD on the new internal, and make the new HD bootable.

You might have to (should) run the "Disk Utilities" program to format your new internal HD to the "Mac OS Extended (Journaled)" file system. It seems that 99% of the disks you buy are pre-formated for Windows, so be sure to check the "Options" in the Disk Utility to make the new drive MacOS bootable before you format it. If not, you will finish the SuperDuper copy and find out there is something not right about your new HD.

After you are done (about 2 or 3 hours), reboot normally.

Keep the external HD (original) around for awhile - a week or so - to confirm everything went okay, then you can reformat it and use it extra storage, time machine, or what ever.

Hello,
First post from a switcher. I plan on upgrading my new (NOV purchas) MBP 13.3 from the 160gb HDD to a larger cap drive this week. If I follow what the post above is saying if I do the superduper clone, the computer will read the new HD exactly like the old one, programs and all as if I never took the other one out? Basicly no reinstaling apps, no reentering iTunes autorizations, everything exactly the same?

Technically, yes. However, you know that nothing is ever 100% foolproof, so while chances are high that things will go off without a hitch, don't discount the possibility that you might experience a hiccup or two in the process.

Don't worry though, you have nothing to lose in trying except time. All your original files will still be intact on the original drive, and if anything does go wrong, you can simply wipe the new drive clean and either start over or just install everything from scratch and copy over your personal files from the old drive.

Technically, yes. However, you know that nothing is ever 100% foolproof, so while chances are high that things will go off without a hitch, don't discount the possibility that you might experience a hiccup or two in the process.

Don't worry though, you have nothing to lose in trying except time. All your original files will still be intact on the original drive, and if anything does go wrong, you can simply wipe the new drive clean and either start over or just install everything from scratch and copy over your personal files from the old drive.

I agree.

I had to go through this process twice because I didn't pick the right option when I formatted the new HD. But I never lost anything, and at the end of the process, everything was exactly like I had before - except I now had 300GB free space.

My "problem" was that even though I selected the "Mac OS Extended" file system to reformat the HD, I didn't check the "options" panel. I found out later, when I tried to install Boot Camp, that the partition was still set with "Master Boot Record" instead of "GUID partition Table". The "Master Boot Record" is a left over from when I bought the drive and the manufacture had it formatted for Windows. The drive would boot okay, but when the Boot Camp Assistant tried to resize the partition, it failed.

If you have Boot Camp installed, it complicates the process. There are extra steps, but it still works okay. If you don't have Boot Camp, it's a piece of cake.

I reinitialized the partition with the "GUID Partition Table" checked, re-ran SuperDuper and never looked back.

I used this method for an upgrade a time or two The only thing you may run into is that sometimes I have to boot the computer with the install disk afterwards and mark the new hard drive as the boot device.

Well put in the new 500GIG HD and upgraded to 4MB of memory today following Apples instructions, and the advice above on superduper, and all went off without a hitch. Way easy to do than i made it out in my mind to be, none the less thanks for the info.